CCNA Study Guide

By Dustin Hawkins,2014-06-17 08:17
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CCNA Study Guide ...

    it is faster and more efficient since it doesn’t have OSI Model A P S T N D P acknowledgements. Upper layers7, 6, 5 don’t deal with data delivery, provide standardization of how applications share data and communicate with one another. 7. Application Doesn’t provide services to the other layers, but Routing Protocols it does communicate with user applications and selects the Distance Vector Routing - Routing protocols that send appropriate network application for those applications. their routing tables to their neighbors; uses the distance to 6. Presentation - Data representation, encryption, and a remote network to find the best path (RIP and IGRP) compression. Supports different protocols for text, data, Counting to Infinity - Distance vector routing error that sound, graphics, and images. (ASCII, EBCDIC, MIDI, MPEG,

    can be remedied by Maximum Hop Count, Split GIF, JPEG, PICT, TIFF)

    5. Session Establishes, manages and terminates sessions Horizons, Route Poisoning, and Hold-Down timers. between apps. A session is a dialog between Presentation Link State Routing - Sends the state of its own interfaces layers of two or more systems. Protocols include NFS, SQL, to every router in the network; determines the entire ASP, and RPC. network topology, then uses SPF (Shortest Path First) Middle provides end-to-end data transportation services to the upper algorithm to find best route. (OSPF,EIGRP(hybrid DV+LS)) layers Link State routing problems - Router resource usage, 4. Transport- Performs flow control by buffering, multiplexing, bandwidth consumption, and update synchronization. and parallelization. Provides end-to-end services by Solutions - Lengthening the update frequency, segmenting upper layers, establishing end-to-end connection,

    sending segments, and ensuring reliable data transport. Data exchanging route summaries, using time stamps, or Unit is Segments. using sequence numbers can remedy the problems. Lower 3. Network Determines the best path from one network to Routing Problems: another (path determination), packet switching, also known Convergence Time it takes all routers to receive an as the domain of routing. Routers work at this layer. Uses update and agree on optimal routes through the routing protocols (RIP, OSPF), and routed protocols (IP, IPX) internetwork. to provide logical addresses. Data Unit is Packets Routing Loops - When two or more routers have not yet 2. Data Link - Made up of the LLC and MAC sublayers. converged and are broadcasting inaccurate routes. Bridges/switches work at this layer. Allows upper layers to work independently of the physical media. Performs physical Routing Problems’ Solutions: hardware addressing, Optional flow control, and error

    notification. LLC (Logical Link Control) is where framing Hold-downs - Prevent regular update messages from occurs by the IEEE standards. MAC sublayer deals with reinstating a route that is down. hardware functions and maintains the physical address (48 Route Poisoning - If a router's connected network goes bits, burned onto card by manufacturer) of the network card down, it sets its hop count to the maximum amount to going into each host or gateway. Data Unit is Frames. make the network unreachable. 1. Physical - Where signals are converted to bits for transport Split Horizons - Specify that a router can't send across a LAN. Mechanical and electrical functions of the OSI information about a route out the interface they originated model. Communicate with peer layers regarding activating, from. maintaining, and deactivating a circuit. Data Unit is Bits. Maximum Hop Count - DV (RIP) permits hot count of up

    to 15. So a packet that is caught in a routing loop will only Devices at the OSI Layers thtravel 15 hops, on the 16 the network is deemed Device Layer Data Unit unreachable and the packet is discarded. Router Network Packets Bridge Data Link Frames Configuring Routing Protocols Switch Data Link Frames Configuring Static Routes Hubs Physical Bits Syntax: ip route [dest] [mask] [next_hop | exit_int] 5 Steps of data encapsulation: Example: 1. User information is converted to data (App Session) R_3(config)#ip route serial0 2. Data is converted to segments (Transport) Configuring RIP (Routing Information Protocol): 3. Segments are converted to packets (Network) Syntax: Router(config)#router rip 4. Packets are converted to frames (Data Link) Router(config-router)#network <network #> 5. Frames are converted to bits (Physical) Example: Router(config)#router rip Connection Oriented vs. Connectionless (Transport) Router(config-router)#network Connection Oriented requires a unique session or pipe to Router(config-router)#network be established (TCP). Setup and maintenance procedures Configuring IGRP (Interior Gateway Routing Protocol) are performed to ensure delivery of messages. Establishes Syntax: Router(config)#router igrp <autonomous system #> a Virtual Connection between the two devices. Router(config-router)#network <network #> Connectionless can be sent any time to any destination Example: without any setup or acknowledgement (UDP). It is up to Router(config)#router igrp 200 the application to determine if the data gets to the Router(config-router)#network destination, instead of the protocols. The advantage is that Router(config-router)#network

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    debug ipx routing Displays messages relating to IPX Checking Router Status Commands activity routing activity.

    debug ipx routing Displays messages relating to IPX Basic Router Operations events routing events. enable | disable Enter privileged mode | exit to usr debug ipx sap Debug IPX sap packets Ctrl+P Previous command Backup Configurations Ctrl+N Next command copy run start Copy current config to NVRAM Ctrl+A Move to beginning of the line copy start run Copy config from NVRAM to RAM Ctrl+E Move to the end of the line copy run tftp Copy config to TFTP server Ctrl+F Forward one character copy tftp run Restore config from Server Ctrl+B Back one character copy flash tftp Backup IOS to TFTP server Esc+B Moves back one word at a time copy tftp flash Restore IOS from TFTP server Esc+A Moves forward one word at a time boot system flash Tells router which IOS file in flash <shift>+<ctrl>+6 X Shift between telnet sessions [filename] to boot. <tab> Completes commands boot system tftp Tells router which IOS file to Viewing Router Information [filename] request from tftp server show version IOS Version Information Set Passwords (Global Config Mode) show memory Memory statistics. line con 0 -Selects Console line aux 0 -Selects Auxiliary show protocols Active network routing protocols. line vty 0 4 -Selects Telnet show running-config Current config in RAM. login -Allows logins and show startup-config Saved config in NVRAM. password cisco -sets the password to cisco show interfaces Interface status + config. enable password cisco -Set password for privilege mode

    to cisco show flash IOS file and free space. enable secret cisco2 -Set encrypted password to cisco2 Cisco Discovery Protocol (CDP)

    show cdp cdp info (broadcast holdtime). show cdp neighbor This shows all devices directly Configure Logical Addresses connected to the router, hold time, TCP/IP -32 bits local and remote port, ID, platform Syntax: and capability info. Router#configure terminal show cdp neighbor Adds IP / IPX addresses to above Router(config)#interface <type> <Number> detail info. Router(config-if)#ip address <addr> <mask> show cdp entry Shows info for all entries ( *) or Router(config-if)#no shut only one (NAME). [*(all) | NAME] Example: show cdp traffic Shows traffic statistics. Router(config)#interface Ethernet 0 show cdp interface Display info about the interfaces on Router(config-if)#ip address [type number] which CDP is enabled cdp run Enables CDP (global configuration) Router(config-if)#no shutdown cdp enable Enables CDP for an interface IPX (only configure network ID, MAC is used for host ID) 80 bits (interface configuration mode) Syntax: Specifies CDP updates frequency. cdp timer seconds Router#configure terminal Specifies the hold time to be sent in cdp holdtime seconds Router(config)#ipx routing the CDP update packets. Router(config)#interface <type> <Number> TCP/IP Router(config-if)#ipx network <#> encapsulation no ip routing Disables IP routing. <type> show ip route View IP routing table. Router(config-if)#no shutdown show ip interface IP